Connection Problem of Serial Device Server: After serial device server establishing connection, the server receives the unknown character

 

After the connection is established, the device sends unknown characters to the server.  Reasons: Maybe use Telnet to use Telnet protocol (This phenomenon will only exist in the old firmware, which is the firmware version <2008, this problem does not exist in 2008 and later firmware.)

Telnet Protocol

 

Module Id type

 

Solution: Select RAW; ID type is set to 0.